Approximately 300,000 artificial hips are implanted annually, in the United States alone. An increasing number of younger, more physically active patients has prompted the orthopedic implant industry to develop more durable, wear-resistant bearing materials, for example, metal-on-metal or ceramic-on-ceramic bearings. However, although demand for low volumetric wear of hard-on-hard bearings remains strong, sales of metal-on-metal bearings has declined, due to concerns about severe adverse tissue reaction to metal ions and metal debris. For example, the August 2010 recall of the ASR™ hip by DePuy has focused intense media, technical publication and legal scrutiny on metal-on-metal bearings across the industry.
Ceramic-on-ceramic bearings are an alternative solution; however, those bearings have also suffered a major setback over the last 4 years, due to a growing incidence of in vivo squeaking.